What is the purpose of the ESS TRU 2 Transfer Contractor?

• A. After The Failure Of Both AC BUS 2 And ESS TRU 1, Allows AC ESS BUS To Power The ESS TRU 2
• B. It Powers The Cabin Lights
• C. It Transfers DC Power To The ESS Bus
• D. It Powers The Hydraulic System

Answer: (A)

The essential idea here is how the ESS TRU 2 Transfer Contractor keeps critical power available by re-routing the power feed to the TRU 2 when the usual sources fail. The ESS TRU 2 is a transformer-rectifier unit that converts AC from the essential AC power sources into DC to feed the essential DC bus. If AC BUS 2 and ESS TRU 1 both fail, the transfer contractor switches the feed so that AC ESS BUS power can still drive ESS TRU 2, preserving DC power to the essential bus and the systems connected to it. This is why option describing this reconfiguration to keep ESS TRU 2 powered is the correct one. The other options describe functions that aren’t what this transfer path provides—for example, cabin lights aren’t specifically powered through this path, and the TRU’s role is to supply DC from AC, not to transfer DC power to the ESS bus or to power the hydraulic system.